This invention relates to a card-form medium, such as optical cards and magnetic cards, and a data recording device for recording data on the medium.
In a recording and/or reproduction system utilizing, for example, an optical card as the recording medium, the recording and/or reproduction operation is effected by reciprocally moving the optical card, having a plurality of parallel tracks, in the track extending direction as well as in the direction perpendicular to the track extending direction. This reciprocal movement is carried out relative to an optical head for performing recording on and/or reproduction from the optical card.
An optical card used in such a system is disclosed in, for example, Japanese Patent Disclosure No. 58-500462. In this Japanese Patent Disclosure, various optical cards have been proposed.
FIG. 5 shows an example of the optical card corresponding to that disclosed in the Japanese Patent Disclosure 58-500462. Optical card 1 has data recording area 2 on which a plurality of tracks extending in the longitudinal direction are parallel arranged in the width direction. ID sections 3 and 4, containing data such as track addresses, are provided on both ends of the tracks in recording area 2. Recording tracks for recording data are formed between ID sections 3 and 4.
FIG. 6 exemplifies an enlarged view of the track of optical card 1 shown in FIG. 5. The track is formed of recording track 6 and guide tracks 7 used for achieving the tracking. ID section 3 is used to record data section 8 on recording track 6 and to reproduce data section 8 from the left end thereof in the drawing. ID section 4 is used to reproduce data section 8 from the right end thereof in the drawing.
As shown in FIGS. 7A and 7B, ID sections 3 and 4 respectively include synchronizing sections (SYNC) 3a and 4a for attaining synchronization of self-reproduction clock, synchronizing patterns (DM) 3b and 4b indicating the head of data, and track number sections (TRACK NO.) 3c and 4c having track numbers recorded therein. Further, as shown in FIG. 7C, data section 8 includes data section synchronizing patterns (DM) 8b and 8c indicating the head of data provided on both sides of necessary information (DATA) 8a, and data section synchronizing sections (SYNC) 8d and 8e for attaining synchronization of self-reproduction clock. Data section synchronizing section 8d and data section synchronizing pattern 8b are used when data 8a is reproduced from the left end in the drawing, and data section synchronizing section 8e and data section synchronizing pattern 8c are used when data 8a is reproduced from the right end in the drawing.
FIG. 8 shows the construction of a recording/ reproduction device, adapted to optical card 1 described above. With this construction, data is recorded on the optical card by modulating recording data D11 from sector buffer memory 11 by modulator 12, and controlling laser driver 13 by modulation signal E12 thus obtained, in order to adjust the driving current so that output power of a semiconductor laser in optical unit 14 exceeds the sensitivity (recording threshold) of recording material of the optical card. In this case, the recording of the data section is effected only in one direction of the relative reciprocal movement between optical unit 14 and the optical card in the track extending direction, for example, only in a direction from left to right in FIG. 5.
In order to reproduce data recorded in the data section, output signal E14 from optical unit 14 is first amplified by pre-amplifier 15, then converted into binary coded reproduction signal E16 by signal processor 16, and demodulated by demodulator 17. Demodulated output data D17 from demodulator 17 is stored in sector buffer memory 11.
In the data reproducing operation, demodulated data D17 is stored from the head of sector buffer memory 11 according to address data D18 (moving direction signal) from controller 18 when the optical card moves relative to optical unit 14 in the same direction as in the data recording operation, and is stored from the tail of sector buffer memory 11 when the optical card moves in the opposite direction.
However, in the data recording method described above, the data recording direction is fixed in a preset direction. Consequently, it becomes necessary to re-set the optical card or optical unit to the predetermined record starting position after completing one track data recording, in case where data is successively recorded over a plurality of tracks, for example. Further, even when one track data is used for recording, it is necessary to set the optical card or optical unit to the starting position before recording, if it is located in a position opposite to the record starting position. For this reason, time for data recording is liable to become long and the efficiency or convenience is worsened. (First Problem)
The optical card has a memory capacity of several thousand to ten thousand times that of a magnetic card. Although data cannot be erased in an optical card as in an optical disc, it has a memory capacity as large as 1 to 2 M bytes. Therefore, it has been, considered to use the optical card as a bankbook, portable map, prepaid card for purchase or the like.
In the prior art, in order to record data on the optical disc, one track is divided into a plurality of sectors and access is made for each sector. In this case, each sector has an ID section (which is generally preformed) indicating the address thereof, and a data section for data readout/write-in. In the ID section, a track number, a sector number, a code indicating the head or tail of the disc, an error detection/correction code, and the like are recorded as a sector address.
A control device for accessing the optical disc is constituted to access a desired sector after reading out information in the ID section.
Generally, in the optical card, the amount of data to be written into one track is 512 to 1024 bytes, and it is a common practice to use one track as one sector. However, there are certain cases wherein the amount of 512 to 1024 bytes data to be processed is too large for accessing the card and it may be preferably set to 64 to 128 bytes. In this case, since the optical card is a read-only medium, part of the recording region cannot be used. In order to solve this problem, it is necessary to use another card format in which one track is divided into a plurality of sectors as in the optical disc and access is made for each sector.
FIG. 25 shows an optical card having such a card format. Optical card 1 has four ID sections 4ax, 4bx, 4cx, and 4dx, and four data sections 5ax, 5bx, 5cx, and 5dx, provided in optical recording area 2x in which a plurality of parallel tracks 6x are formed. ID sections 4ax, 4bx, 4cx, and 4dxare precoded to designate respective addresses of data sections 5ax, 5bx, 5cx, and 5dx.
As shown in FIG. 26, each of ID sections 4ax, 4bx, 4cx, and 4dx includes PLL synchronizing gap section 261, byte synchronizing pattern 262, track number 263, sector number 264, and error correction code 265, and has a memory capacity of 18 bytes, for example.
With optical card 1x, data readout/write-in with respect to a target sector in the target track can be effected, by first reading out the contents of ID sections 4ax, 4bx, 4cx, and 4dx to detect the current track and sector positions and then, accessing the target track and the target sector while comparing the detected track/sector positions with the target track/sector positions.
However, in optical card 1x of FIG. 25, it is necessary to use many ID sections for accessing data sections 5ax, 5bx, 5cx, and 5dx, equal in number to the data sections. For this reason, the amount of data that can be used for other purposes than ID's is reduced. This problem becomes more serious when the number of divisions in one track increases and the area occupied by the ID section becomes large. (Second Problem)